Electron-phonon interaction of one-dimensional and two-dimensional surface states in indium adlayers on the Si(111) surface

Abstract

We performed angle-resolved photoelectron spectroscopy measurements on one-and two-dimensional (1D and 2D) metallic surface states in indium layers on the Si(111) surface as a function of temperature. The temperature dependence of surface-state energy widths was used to estimate the electron-phonon coupling constant lambda. The 2D metallic surface states of the root 7 x root 3-In layer above one monolayer exhibit lambda = 0.8 similar to 1.0, similar to the value of bulk indium 0.9. This is discussed in the light of a recent structure model with a double indium layer and the relatively high superconducting transition temperature of this surface. On the other hand, the lambda's of two 1D surface states of the 4 x 1-In surface with one monolayer of indium are much higher than that of root 7 x root 3-In, reaching 1.8, which is the largest ever reported for a surface state. The origin of the enhanced electron-phonon coupling and its relationship to the charge-density-wave phase transition of this surface are discussed. DOI: 10.1103/PhysRevB.86.245408